I am currently using a Focusrite Clarett 4Pre. It does everything I want; 4 balanced channel output controlled by a single knob, Thunderbolt connectivity, even IOS remote.
The FPGA allows selection of routing, number of outputs, and input selection. The dac chip is a four channel AK4413.
The only downside is the volume control is internal in the dac chip. Most listening is at -40 - -60dB. With a 24 chip like the AK4413, the attenuation is 7 - 10 bits. Which leaves 14 -17 available for playback of the files.
AKM has a 32 but dac chip that looks identical. It is the AK4414. It does not do DSD, but neither does the Clarett. It is possible to just swap the AK4414 for the AK4413? If this is a drop in the built in attenuator would have 32 bits to play with instead of with instead of 24. Should be a big improvement.
I have a friend with the equipment to change out the 44 pin chip without damage. But do not want to take chance on bricking the 4Pre if the 32 bit four channel dac is not a drop in replacement for the 24 bit.
The FPGA allows selection of routing, number of outputs, and input selection. The dac chip is a four channel AK4413.
The only downside is the volume control is internal in the dac chip. Most listening is at -40 - -60dB. With a 24 chip like the AK4413, the attenuation is 7 - 10 bits. Which leaves 14 -17 available for playback of the files.
AKM has a 32 but dac chip that looks identical. It is the AK4414. It does not do DSD, but neither does the Clarett. It is possible to just swap the AK4414 for the AK4413? If this is a drop in the built in attenuator would have 32 bits to play with instead of with instead of 24. Should be a big improvement.
I have a friend with the equipment to change out the 44 pin chip without damage. But do not want to take chance on bricking the 4Pre if the 32 bit four channel dac is not a drop in replacement for the 24 bit.
Some discussion of DAC volume control methods and trade offs here:
Volume Control Technologies - Benchmark Media Systems, Inc.
Don't know if it will be useful for you or not, but hopefully at least interesting to take a look at.
Volume Control Technologies - Benchmark Media Systems, Inc.
Don't know if it will be useful for you or not, but hopefully at least interesting to take a look at.
If you are really concerned about this loss of dynamic rangea passive 40dB attenuator before your power amp would put you in the right listening volume range for the cost of a few resistors and some connectors.
Also since both these DACs have an analogue noise floor of 120dB you wont get any dynamic range improvement by changing the part you will be noise floor limited. 120dB is likely much better than your power amp anyway so chances are you dynamic range is limited by your power amp.
Regards,
Andy
Also since both these DACs have an analogue noise floor of 120dB you wont get any dynamic range improvement by changing the part you will be noise floor limited. 120dB is likely much better than your power amp anyway so chances are you dynamic range is limited by your power amp.
Regards,
Andy
As far as adjusting volume digitally inside the DAC or prior to the DAC, it may help to reduce distortion due to intersample overs by reducing the gain digitally by 3.5dB. That's enough to prevent the reconstruction filter from distorting on such peaks.
Other than a fixed -3.5dB digital level adjustment, I would agree that active or passive analog level reduction after the DAC would probably make more sense than swapping DACs.
Regarding bits to play with, no DACs are actually good to 24 bits, maybe more like 18-20 bits at best (due to noise floor limitations).
Also, digital audio formats at 24 bits and 32 bits actually contain the exact same information. Files at 24-bits use a fixed-point data format, and 32-bit files use floating-point data, but the number of significant bits is still 24. Not sure when you mentioned 32 bits if you were talking about digital audio formats or something else.
Other than a fixed -3.5dB digital level adjustment, I would agree that active or passive analog level reduction after the DAC would probably make more sense than swapping DACs.
Regarding bits to play with, no DACs are actually good to 24 bits, maybe more like 18-20 bits at best (due to noise floor limitations).
Also, digital audio formats at 24 bits and 32 bits actually contain the exact same information. Files at 24-bits use a fixed-point data format, and 32-bit files use floating-point data, but the number of significant bits is still 24. Not sure when you mentioned 32 bits if you were talking about digital audio formats or something else.
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I also agree that passive 40dB attenuation before your power amplifier is the best solution because noise floor limitation exists in an analog domain. The difference between 24bits and 32bits exists only in a digital domain. The output of AK4413 wants to catch up the digital input data. The accuracy depends on the input resolution. That's why 32 bits or more is preferable for DSM in a digital domain, especially below -100dBFS. But this is virtual. You can't get the exact copy of calculated digital data from a DAC chip in an analog domain. If you measure SNR at the input of a loudspeaker, more than 100dB SNR is rare as long as I have measured.
Reply is gone - cell phone post.
I have compared the datasheets for the AK4413 and AK4414. The specs, filters, and pinouts are identical.
Knowing the digital attenuator reduces volume by dropping bits this looks like an issue with a 24 bit dac chip. The datasheet shows a 255 step attenuator with a range of 0 to -128 dB for both.
I wish Focusrite had used the AK4414 to start with. I have a dac with dual ES9018 dac chips and it uses the internal volume controller. Works great. Since the 32 bit range has so many unusable bits, dropping 7 - 10 bits is no issue. Dropping 10 bits with a 24 bit unit is an issue with my 96/24 files. They may only be 18 - 20 bit resolution, but at high attenuation the dac only has 14 available.
The AK4414 is 4 dollars more than a AK4413 at digikey at singles prices. Eight to twelve dollars. I am sure at Focusrite qualities the difference is smaller.
I have compared the datasheets for the AK4413 and AK4414. The specs, filters, and pinouts are identical.
Knowing the digital attenuator reduces volume by dropping bits this looks like an issue with a 24 bit dac chip. The datasheet shows a 255 step attenuator with a range of 0 to -128 dB for both.
I wish Focusrite had used the AK4414 to start with. I have a dac with dual ES9018 dac chips and it uses the internal volume controller. Works great. Since the 32 bit range has so many unusable bits, dropping 7 - 10 bits is no issue. Dropping 10 bits with a 24 bit unit is an issue with my 96/24 files. They may only be 18 - 20 bit resolution, but at high attenuation the dac only has 14 available.
The AK4414 is 4 dollars more than a AK4413 at digikey at singles prices. Eight to twelve dollars. I am sure at Focusrite qualities the difference is smaller.
What about the control register set for both? If any differences there, you might need to write a new software driver.
Perhaps they did not use the more expensive AK4414 because they actually understand binary arithmetic.
This was my main concern. I can swap the 44 pin chip. Writing a driver is way beyond my skills.
I think the internal volume control is great when there is the option of 2 channel, 4 channel, and other assignable outputs. Having a single knob to adjust is very user friendly.
It just needs 32 bits to work with.
Using an analog controller for a four channel balanced signal is doable. An eight wafer Shallco or some other type of resistor based switch would work.
Swapping the stock dac chip for a 12.00 replacement would be easier and way cheaper. Just do not know if it would still work after the swap.
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